The goals of this program are to examine in detail factors regulating oxygenation of blood and tissues and the effects of lung disease on systemic and pulmonary arterial blood pressures. A detailed characterization of respiratory gas exchange, pulmonary blood volume and instantaneous pulmonary arterial blood flow and pressure will be undertaken to assess the interaction of air and blood in lungs of patients with diffuse, chronic intersitial lung disease and in an animal model of diffuse granulomatous lung disease. Respiratory muscle function and metabolism will be examined under conditions of hypoxemia, acidosis, and at high levels of contractile effort to delineate the role of respiratory muscle in maintenance of gas exchange. The role of myoglobin in oxygen transport to muscle fibers will be examined. A systematic study of the in vivo effects of intravenously administered antibody specific for the enzyme responsible for the conversion of angiotensin I to angiotensin II will be undertaken. The precise cytologic localization of angiotensin-converting enzyme will be studied by electron microscopy.